The diameter of NFCs ranges from 10 to 37 nm,
similar to that of some previously reported cellulose
nanofibers obtained by ultrasonic method in literatures [34]
(10–40 nm), [35] (30–100 nm), and [36] (2–50 nm). In
addition, it can be found that the NFCs in our paper have
narrower diameter distribution. Moreover, the average size
(d) and standard deviation (r) were calculated as 22.67 and
5.79 nm, respectively.